People with a very high BMI (body mass index), considered obese and morbidly obese, also typically suffer from high levels of inflammation and hypoventilation. Given these chronic ailments, when COVID-19 attacks the system, the body can over-react based on the already damaging level of inflammation that has caused a weakened immune system. In the case of hypoventilation, if the body is already struggling to ventilate properly, and you add the damaging effects of COVID-19 (acute respiratory distress), an already weakened ability to breath and ventilate is further compromised. The result will be life threatening, likely requiring the aid of a ventilator.
For more information beyond this article, please refer to my previous blog post where I referenced studies on COVID-19 patients that drew a strong correlation between severe symptoms and those suffering from obesity, diabetes and high blood pressure. https://wordpress.com/block-editor/post/business-fit.org/829